This invention relates to a process for the production of a flavouring agent by enzymatic hydrolysis of proteins.
Materials rich in proteins, such as for example oilseed cakes, pulses, cereal gluten or lactic proteins, are widely used in hydrolyzed form as a starting material in the composition of dehydrated or liquid soups, sauces and seasonings.
In this context, a peanut or soybean cake, for example, is normally subjected to hydrolysis with concentrated hydrochloric acid, the hydrolyzate is neutralized with sodium hydroxide, the insoluble fractions are removed, the hydrolyzate is optionally subjected to filtration, decoloration, concentration and/or drying and is then used as a flavouring agent as such, or after reaction with reducing sugars, for example.
A process such as this for the production of a flavouring agent by acidic hydrolysis of proteins is attended inter alia by the disadvantage that the amino acids produced during hydrolysis are degraded.
If, for this reason, it is preferred to subject a material rich in proteins to enzymatic hydrolysis, the familiar problem of bitterness of the hydrolyzate caused by bitter peptides produced during hydrolysis is encountered.
Various processes have been proposed with a view to avoiding or eliminating this bitterness, in particular by carrying out the enzymatic hydrolysis under such conditions that the production of bitter peptides is reduced, by extracting the bitter peptides from the hydrolyzate or by degrading the bitter peptides.
EP 223 560, for example, describes a process in which casein or an isolate of soya proteins is hydrolyzed with a proteinase, after which the bitterness of the product obtained is eliminated by rehydrolysis with an aminopeptidase derived from a strain of Streptococcus lactis.